From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Xen Devel <xen-devel@lists.xensource.com>,
KVM <kvm@vger.kernel.org>,
Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
Peter Zijlstra <peterz@infradead.org>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andi Kleen <andi@firstfloor.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Attilio Rao <attilio.rao@citrix.com>,
Thomas Gleixner <tglx@linutronix.de>,
Virtualization <virtualization@lists.linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>,
Avi Kivity <avi@redhat.com>
Subject: Re: [Xen-devel] [PATCH RFC V6 0/11] Paravirtualized ticketlocks
Date: Tue, 17 Apr 2012 08:24:16 +0530 [thread overview]
Message-ID: <20120417025416.GA10184@linux.vnet.ibm.com> (raw)
In-Reply-To: <1334594195.14560.236.camel@zakaz.uk.xensource.com>
* Ian Campbell <Ian.Campbell@citrix.com> [2012-04-16 17:36:35]:
> > > The current pv-spinlock patches however does not track which vcpu is
> > > spinning at what head of the ticketlock. I suppose we can consider
> > > that optimization in future and see how much benefit it provides (over
> > > plain yield/sleep the way its done now).
> >
> > Right. I think Jeremy played around with this some time?
>
> 5/11 "xen/pvticketlock: Xen implementation for PV ticket locks" tracks
> which vcpus are waiting for a lock in "cpumask_t waiting_cpus" and
> tracks which lock each is waiting for in per-cpu "lock_waiting". This is
> used in xen_unlock_kick to kick the right CPU. There's a loop over only
> the waiting cpus to figure out who to kick.
Yes sorry that's right. We do track who is waiting on what lock at what
position. This can be used to pass directed yield hints to host
scheduler (in a future optimization patch). What we don't track is the
vcpu owning a lock, which would have allowed other spinning vcpus to do
a directed yield to vcpu preempted holding a lock. OTOH that may be
unnecessary if we put in support for deferring preemption of vcpu that
are holding locks.
- vatsa
next prev parent reply other threads:[~2012-04-17 2:54 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-21 10:20 [PATCH RFC V6 0/11] Paravirtualized ticketlocks Raghavendra K T
2012-03-21 10:20 ` [PATCH RFC V6 1/11] x86/spinlock: replace pv spinlocks with pv ticketlocks Raghavendra K T
2012-03-21 13:04 ` Attilio Rao
[not found] ` <4F69D1D9.9080107@citrix.com>
2012-03-21 13:22 ` Stephan Diestelhorst
[not found] ` <2425963.NBpIGX9T40@chlor>
2012-03-21 13:49 ` Attilio Rao
[not found] ` <4F69DC68.6080200@citrix.com>
2012-03-21 14:25 ` Stephan Diestelhorst
[not found] ` <1363312.nixp29LUbv@chlor>
2012-03-21 14:33 ` Attilio Rao
[not found] ` <4F69E6BB.508@citrix.com>
2012-03-21 14:49 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 2/11] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 3/11] x86/ticketlock: collapse a layer of functions Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 4/11] xen: defer spinlock setup until boot CPU setup Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 5/11] xen/pvticketlock: Xen implementation for PV ticket locks Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 6/11] xen/pvticketlocks: add xen_nopvspin parameter to disable xen pv ticketlocks Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 7/11] x86/pvticketlock: use callee-save for lock_spinning Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 8/11] x86/pvticketlock: when paravirtualizing ticket locks, increment by 2 Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 9/11] x86/ticketlock: add slowpath logic Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 10/11] xen/pvticketlock: allow interrupts to be enabled while blocking Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 11/11] xen: enable PV ticketlocks on HVM Xen Raghavendra K T
[not found] ` <20120321102107.473.89777.sendpatchset@codeblue.in.ibm.com>
2012-03-21 17:13 ` [PATCH RFC V6 2/11] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Linus Torvalds
2012-03-22 10:06 ` Raghavendra K T
2012-03-26 14:25 ` [PATCH RFC V6 0/11] Paravirtualized ticketlocks Avi Kivity
2012-03-27 7:37 ` Raghavendra K T
[not found] ` <4F716E31.3000803@linux.vnet.ibm.com>
2012-03-28 16:09 ` Alan Meadows
2012-03-28 18:21 ` Raghavendra K T
2012-03-29 9:58 ` Avi Kivity
2012-03-29 18:03 ` Raghavendra K T
2012-03-30 10:07 ` Raghavendra K T
[not found] ` <4F7585EE.7060203@linux.vnet.ibm.com>
2012-04-01 13:18 ` Avi Kivity
2012-04-01 13:48 ` Raghavendra K T
2012-04-01 13:53 ` Avi Kivity
2012-04-01 13:56 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
[not found] ` <4F7976B6.5050000@linux.vnet.ibm.com>
2012-04-02 12:15 ` Raghavendra K T
2012-04-05 9:01 ` Avi Kivity
2012-04-05 10:40 ` Raghavendra K T
2012-04-05 8:43 ` Raghavendra K T
2012-03-30 20:26 ` H. Peter Anvin
2012-03-30 22:07 ` Thomas Gleixner
2012-03-30 22:18 ` Andi Kleen
2012-03-30 23:04 ` Thomas Gleixner
2012-03-31 0:08 ` Andi Kleen
2012-03-31 8:11 ` Ingo Molnar
2012-03-31 4:07 ` Srivatsa Vaddagiri
2012-03-31 4:09 ` Srivatsa Vaddagiri
2012-04-16 15:44 ` Konrad Rzeszutek Wilk
2012-04-16 16:36 ` [Xen-devel] " Ian Campbell
2012-04-16 16:42 ` Jeremy Fitzhardinge
2012-04-17 2:54 ` Srivatsa Vaddagiri [this message]
2012-04-01 13:31 ` Avi Kivity
2012-04-02 9:26 ` Thomas Gleixner
2012-04-05 9:15 ` Avi Kivity
2012-04-02 4:36 ` [Xen-devel] " Juergen Gross
2012-04-02 9:42 ` Ian Campbell
2012-04-11 1:29 ` Marcelo Tosatti
2012-03-31 0:51 ` Raghavendra K T
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